Aquatic invasive species (AIS)
Aquatic invasive species (AIS) are non-native species that can have negative impacts on our health and threaten commercial, agricultural, aqua-cultural or recreational activities dependent on Montana's lakes and rivers.   AIS Prop                              

Aquatic invasive plants like flowering rush, Eurasian watermilfoil, and curlyleaf pondweed have been introduced to Montana. They are impeding recreation, clogging irrigation systems, and destroying water quality for fish and other wildlife.  Once these plants are introduced to a water body, they are nearly impossible to eradicate.

Zebra and quagga mussels would have an even greater impact than aquatic invasive plants. Once introduced, it is unlikely they will ever be removed unless the infestation is caught very early. Currently, there is no approved management option to control zebra mussels if they are introduced into Montana. The few chemical treatments that could kill the mussels would also kill may native species.

The zebra and quagga mussel have immense economic impacts. Most economic impact assessments associated with mussel invasion are based on costs incurred by industries operating dams, power and water treatment plants, and associated losses to the local economy and tax base. Estimates in the U.S. indicate that hydropower industries are incurring $1 billion dollars annually to maintain their operations after mussels invade, and estimated annual economic losses suffered by regions in the event of a mussel infestation are staggering:

  • $100s of millions annually in the Columbia River Basin;
  • $94.5 million annually to the State of Idaho; and
  • $22.4 million annually in the Lake Tahoe region.


Unfortunately, most economic impact assessments do not include costs to irrigators and agriculture. Therefore, the economic costs associated with AIS are significantly underestimated.

The potential economic impact of an infestation to the Flathead Basin or State of Montana does not exist. It is likely that it would be measured in the millions of dollars similar to Idaho. The economic impact could be felt in the following ways:
  • 10 to 30% decrease in tourism; 
  • 10 to 20% increase in utility rates;
  • 10 to 20% decrease in property values and taxes;
  • 10 to 20% increase in maintenance and operations for water infrastructure; and
  • Millions of dollars of capital costs for new infrastructure.
In Montana, recreational boating and fishing contribute $671 million to Montana's economy. A 10% decrease would equal a loss of $67 million to local communities. Many states have made it a priority to prevent mussel introduction to the Northwest.  And ounce of prevention is worth a pound of cure!
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Caryn Miske Executive Director
Flathead Basin Commission
655 Timberwolf Parkway
Kalispell Montana 59901
406-240-3453 e-mail:


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